Well, hopefully PvP has a solid foundation, especially since Yoshi is personally an avid PvPer, but SE isn't really trying to court that crowd. It might be fun, but I would imagine if you try to sell someone on this game as a PvP game they might be disappointed.
My friends are already interested, but I doubt they would even give it a shot if PvP wasn't at least given some thought by the development crew and not just tacked on. They PvE like crazy though too, so it's not like this game isn't already impressing them to some degree. It just feels nice to roll faces once in awhile, you know? Was there PvP in 1.0?